Cements are commonly used as building materials for many reasons. They can be shaped or molded into virtually any form. A liquid cement slurry can be cast into molds to make products such as concrete blocks. The slurry is also useful to form poured cement floors or walls. Flooring compositions are known that are self-leveling and develop high strength over time.
A typical composition for a cementitious binding material includes a silicate cement, such as a Portland cement, sand or other aggregate, water and additives that are specific to the intended use. If the use is a poured flooring, for example, additives may include fluidizing agents to make the floor self-leveling. Set retarders may be provided to give a long open time for working the surface to a smooth, strong finish. Gypsum is optionally added to improve green strength of the setting mixture.
Addition of water to cementitious materials initiates chemical hydration reactions. In an exothermic reaction, water is chemically bound to the cementitious materials, forming crystals whose shape is dependent on the starting material. Often a variety of cementitious materials is used to produce a composition having crystals of a particular shape or that develop certain strength characteristics. As the hydrated crystals form, they become an interwoven crystal matrix. The strength of the crystal matrix depends on how easily the crystals separate from each other.
Slow drying cements increase the cost and time needed for construction. Some sub-contractors are unable to work after, for example, a floor is poured, because it has insufficient strength to bear the weight of the workers and their equipment. There is a need in the art for a cementitious composition that hardens quickly and develops strength quickly.
Another drawback of most cementitious compositions is that they are highly caustic. Highly caustic cement slurries are irritating if brought into contact with skin. Then can also cause degradation of adhesives for tile or carpet. There is a further need for a cementitious composition that is lower in pH so as to be more compatible with people and products that come in contact with it.